Part of the controversial new £230 million bus system in Bristol will have to be closed if it snows - because it is too narrow for snowploughs.
The Metrobus scheme, which is due to open next year, has been beset by delays and soaring costs.
Now, the developers admit that a £49.5million section covering a mile and a half will have to close if it snows.
The section of guided busway, which passes over a railway, is not big enough for snowploughs.
Officials say they are relying on the fact it hardly ever snows in Bristol, with the last major disruptive snowfall occurring in January 2013.
They admit that if it does snows the section would have to close with buses diverted to the traffic-clogged A370 nearby.
The Metrobus scheme is part of a joint project between Bristol, North Somerset and Gloucestershire Councils, to improve transport infrastructure in the West of England.
The project, which is currently under construction, is expected to be completed early in 2018, with a current cost of £230.5million.
It will use hybrid buses with two doors - one for boarding and one for exiting - to travel along a combination of bus lanes and segregated busways.
Normal gritting lorries work fine on the guided busway, and recent testing shows they will fit and work as planned on all sections and bridges on the route.
Last week it emerged that that road layout at another point on the Metrobus route is too narrow to accommodate the new buses.
And another section due to open in October or November has been delayed to Easter because information points where people can buy tickets need installing and testing.